Variable compression ratio internal combustion engine



United States Patent Inventor James C. Hambric Los Angeles, CaliforniaAppl. No. 738,557 Filed June 20, 1968 Patented Aug. 18, 1970 AssigneeKMF Development Corporation a Corp. of California VARIABLE COMPRESSIONRATIO INTERNAL COMBUSTION ENGINE 7 Claims, 2 Drawing Figs.

US. Cl 123/8.07, 123/48 Int. Cl ..F02b 55/14, F02b 75/04 Field of Search123/8, 8(MC), 12(E), 130,48, 48(A),48(A1) References Cited UNITED STATESPATENTS 4,410 4/1930 Allwill ..l23/48(A1)UX 8,582 8/1956 Humphreys..123/48(Al)UX 2,883,974 4/1959 Heising ..l23/48(Al)UX 3,060,910 10/1962McCall l23/l3(D)UX Primary ExaminerCarlton R. Croyle AssistantExaminer-Allan D. Herrmann ArlorneyNilsson and Robbins ABSTRACT: Avariable compression rotary combustion engine is disclosed wherein theeffective size of the combustion chamber changes in accordance withcontrol criteria, to establish favorable compression ratios appropriateto current operating conditions. The engine includes a pair ofsynchronized rotors that are driven by combustion to revolve inintersecting annular passages, combustion occurring insomewhat-separated chambers and expanding into the spaces definedbetween the lobes of the rotors to provide drive power. The combustionchambers are generally cylindrical, having end walls which receive sparkplugs and which are slidably disposed within the cylindrical chambers tovary the effective size of the combustion chamber and thereby accomplishvariation in the compression ratio of the engine. As disclosed, the endwalls are positioned in the combustion chambers by a fluid servo drivearrangement whereby adjustment is substantially continuously adapted tocurrent operating conditrons.

Patented Aug. 18, 1970 QNN O as wmwbi a sq VARIABLE COMPRESSION RATIOINTERNAL COMBUSTION ENGINE BACKGROUND AND SUMMARY OF THE INVENTION Theinternal combustion engine has received a vast engineering effort andpopular forms thereof have become somewhat standard in design, withresulting economy. Generally, such engines are of thereciprocating-piston type as commonly employed in automotive, aircraftand marine applications. It has long been recognized that these enginescould be improved considerably by providing a variable compression ratioto accommodate different operating conditions. However,reciprocating-piston engines of the past do not readily enablevariations in the compression ratio and, in fact, prior efforts todevelop a variable-compression ratio reciprocating-piston engine haveresulted in the conclusion that such an engine is not economicallyfeasible. However, in view of the ever-increasing need for a relativelyclean engine, and one which has the capability of maintaining ratedoperating power at various altitudes, an increased demand exists for anengine with a variable compression ratio.

In the past, internal combustion engines have been proposed which do notutilize reciprocating pistons. Specifically, for example, one form ofsuch an engine has been previously proposed in which a pair of rotors(carrying radially-extending lobes) revolve in a pair of intersectingannular passages, with the lobes acting as both pistons and cylinderheads. For example, one specific form of such an engine is shown anddescribed in U. S. Patent No. 2,674,982 issued April 13, 1954 to WilliamB. McCall. Another patent covering certain improved features of such anengine issued to the same inventor on October 30, I962 bearing thenumber 3,060,910.

In general, the present invention relates to such an engineincorporating a system whereby to accomplish a variation in thecompression ratio in accordance with instant operating conditions. Thesystem affords efficient operation and a very high percentage ofcomplete combustion so as to produce substantially clean or fully-burnedexhaust gases.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment ofthe present inventionis described herein with reference to the appended drawings which alsoform a part of this specification, and in which:

FIGURE 1 is a perspective and diagrammatic representation illustrativeof the operation of an engine constructed in accordance with theprinciples of the present invention; and

FIGURE 2 is a schematic and detailed fragmentary vertical sectional viewtaken through an engine as diagrammatically represented in FIGURE 1,showing the combustion chambers thereof.

As required, a detailed illustrative embodiment of the invention isdisclosed herein. However, it is to be understood that the embodimentmerely exemplifies the invention which may be embodied in many formsthat are radically different from the illustrative structure. Therefore,specific structural and fundamental details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claimsdefining the scope of the invention.

Referring initially to FIGURE l, the somewhat-diagrammatic view isuseful to provide an understanding of the philosophy of operationemployed in the illustrative embodiment. Specifically, a pair of meshedrotors I and 12 are shown mounted for rotation about axes that are inperpendicular relationship. At their outer peripheries, these rotorsdefine lobes which function both as pistons and as cylinder heads in theoperation of the unit as an internal combustion engine. That is,specifically, the periphery of the rotor I0 defines radially-extendinglobes l4 and 16 while the rotor 12 defines similar lobes l8 and 20. Theleading and trailing edges of these lobes are tapered to accommodate aclosely intermeshed synchronized motion between the lobes as the rotorsI0 and 12 revolve on perpendicular shafts 22 and 24. Thus, when therotors l0 and 12 are enclosed by a housing (not shown in FIGURE 1)closed chambers or cavities are developed between the rotors, whichcavities may be expansively driven by combustion bases to provide drivepower as described in considerable detail in the above-referencedpatents.

Considering the basic operation of engines of this type in somewhatgreater detail, a combustion and exhaust flow path for the rotor 10 isgenerally indicated by an arrow 26. An arrow 28 affords a similarindication for the rotor 12. It is to be noted that for illustration,these paths (defined by the arrows 26 and 28) are shown to becontinuous; however, the gas flow is actually intermittent, in chargescarried between the lobes within the enclosing housing (not shown).

During rotation of the rotor 14 (in a counterclockwise direction, asdepicted) a charge of air is carried in a cavity 34 (between the ends orfaces of the lobes l4 and 16) for compression at a location beyond themeshing intersection of the rotors l0 and 12. The air charged is forcedinto a generallycylindrical vertical combustion chamber 36 (of variablelength, located at the rear of the engine) which receives fuel asindicated, through an injection port 38. The fuel, atomized in the aircharge, is then ignited by a pair of spark plugs 40 and 42 that areaffixed in end walls which are telescopically movable in thegenerally-cylindrical chamber 36. The spark plugs 40 and 42 areconnected, for electrical impulses, to a timing generator 43, one wellknown form of which may comprise simply an automotive-enginedistributor.

The expanded gases from the combustion occurring in the chamber 36 moveto encounter in sequence: the walls of the enclosing housing (notshown), a side surface of the lobe 20 (on the rotor 12), and a radialend surface of the lobe 16. The force applied to the side surface of thelobe 20 is transverse or axial to the rotor 12 and therefore hassubstantially no effect but to contain the combustion products forreinforced application to the radial surface of the lobe 16 which isthus yieldably driven. Therefore, as the gaseous products of combustionexpand, to drive the rotor 10 as indicated, they are expanded andeventually are dispensed as exhaust from the rotary channel as indicatedby the arrow 26. It is to be noted that the rotary valve 30 segregatesthe spend exhaust products of combustion from the fresh charge of airthat is received for another combustion.

The operation of the rotor 12 is similar to that described for the rotor10, which is somewhat apparent in view of the symmetry of the two rotorstructures. Specifically, a charge of air is accepted between the lobesof the rotor 12 for compression to a chamber 44 (a cylinder of variablelength) along with atomized fuel which is supplied through a port 46.com bustion of the charge then drives the rotor 12.

In the engine, as disclosed in FIGURE l, the perpendicular shafts 22 and24 (upon which the rotors l0 and 12 are carried respectively) areinterconnected by a gear coupling 48 from which drive power also isprovided. The rotary valve plates 30 and 32 are also coupled to theshaft 22 through a gear coupling 50 (linked to the rotors), all asindicated by conventional dashed lines. The gear couplings 48 and 50synchronize the motion of the rotors I0 and 12 along with that of thevalve plates 30 and 32. In this regard, detailed forms of such systemsare shown and described in the above-referenced patents.

In general, the improvements hereof with respect to the prior art,relate to the system of accomplishing variable compression-ratiooperation in accordance with instant operating conditions. As indicatedabove, this variation is accomplished by changing the effective volumeof the combustion chambers 36 and 44. Specifically, the end walls ofthese generally-cylindrical combustion chambers are movable to establishthe accommodating volumetric changes. In this regard, the compressionratio may be variously adjusted on the basis of various input parametersincluding: engine speed, absolute manifold pressure, altitude, throttleposition, and so on. Of course, in varying applications and according tovarying design criterion, different of these parameters may be employedindividually or in combination.

Considering the illustrative engine structure in greater detail, thehousing associated with each structure of the rotors and 12 issubstantially symmetrical and similar. Therefore, to illustrate thepresent invention, a sectional view is presented in FIGURE 2 whichextends transversely through the combustion chamber 44, showing anexemplary embodiment of the specific structure in full detail.

The structure as shown in FIGURE 2 includes a housing 60 defining theannular cavities 62 in which the rotors 10 and 12 operate andadditionally defining the combustion chamber 64 (separately representedas chamber 44 in FIGURE 1). In general, the combustion chamber 64(FIGURE 2) comprises a cylindrical cavity, the ends of which are closedby pistons 66 and 68, which may be variously disposed within the chamber64 to vary the volume of the chamber and thereby vary the compressionratio of the engine.

The chamber 64 is connected to the annular cavity 62 through anangularly-offset port 70, through which the charge of compressed air isreceived, driven by the moving rotor 12. A fuel passage into thecombustion chamber 64 is provided through a duct 72 threadably receivedin the housing 60 and terminating in a fuel-injection nozzle 74.Ignition of the charge within the combustion chamber 64 is accomplishedby a pair of spark plugs 76 and 78 threadably received in the opposingpistons 66 and 68. When the fuel charge is ignited, gases which are theproduct of combustion, pass from the chamber 64, through the port 70into the cavity 62 to drive the rotor contained therein. The cycle isthen repeated and continuous operation results.

Considering the combustion chamber 64 in greater detail, componentsofthe associated symmetrical structure are, in instances, identified bysimilar reference numerals. The pistons 66 and 68 which are slidablyreceived within the cylindrical chamber 64 are coupled by snap rings 80to sleeves 82 and 84 respectively which in turn are slidably mounted inbores 86 of enlarged diameter. The sleeves 82 and 84 threadably receivevalve annulus members 88 and 90, respectively, over their central,somewhat-enlarged sections. As described in detail below, the centralsections of the sleeves 82 and 84 along with the valve members 88 and 90position the pistons 66 and 68 by pressure-driven spool valve actionunder control of input signals.

The pistons 66 and 68 along with the sleeves 82 and 84 and spool valvemembers 88 and 90 are slaved" or servoed to follow interior cylindermembers 91 and 33 which each include concentric mating cylinders 91 and93 integrally coupled with gear racks 96. The individual end gear racks96 are meshed with gear wheels 98 and 99 (left) and 103 and 104 (right).These gear wheels are also coupled together in pairs through gear wheels100 and 101 (right behind the cylinder 91) and 105 and 106 (left) tomaintain the gear wheels in meshed relationship.

The gear wheels 99 and 104 are mechanically connected to be driven inaccordance with an input signal, as described below, so as to variouslyposition the cylinder structures 91 and 33. In accordance with suchplacement; the sleeves 82 and 84 are similarly positioned to adjust thespacing between the pistons 66 and 68 and accomplish the desiredcombustion ratio.

The fluid power for positioning the pistons 66 and 68 is provided undercontrol from the combustion chamber 64. Specifically, a pair of ports106 and 108 are connected to provide fluid pressure for driving thepistons 66 and 68. The fluid source loops 110 and 112 for providing thispressure are identical; therefore, only the loop 112 is disclosed indetail. The port 108 provides drive pressure to a filter amplifier 114which in turn pressurizes a small reservoir 114 through a check valve116. As a result, a substantially constant source of fluid pressure isprovided by the loops 110 and 112 to input ports 117 and 118respectively. Such fluid pressure serves to slave the pistons 66 and 68to the cylinder structures 91 and 33 as considered below.

In the physical arrangement, the cylinder structures 91 and 33telescopically receive a portion of the spark plugs 76 and 78respectively as well as cylindrical capacitive shields 120 and 122,through which lead wires 124 and 126 pass to be received through elbows128 for connection to the timing generator as a source of electricalspark energy. The elbows 128 are received in the housing 60 throughseals 130, serving to isolate the interior moving components. In thisregard, it is to be noted that the seals 130 dwell on a pair of annularflanged members 132, housing the gear wheels 98 through 105. The housingmembers are fixed in the stepped bores 86 which provide several annularshoulders. Specifically, the bores 86 define internal shoulders (forlimiting inward motion of the pistons 66 and 68), second shoulders 142(defining an enlarged section of the bores to accommodate the slidervalve members 88 and 90), and third shoulders 144 (against which theclosures 134 are fitted).

ln view of the above structural description of the engine as representedin FIGURE 2, a complete understanding thereof may now be bestaccomplished by assuming certain conditions and explaining additionalstructure and operation to accomplish such objectives. Initially, assumethe engine is to provide a variable compression ratio in accordance withthe degree to which the throttle is open and its instant operatingspeed. Accordingly, a tachometer 142 of conventional design manifeststhe speed of the engine by displacing somewhat-resilient cable 144 whichis coupled directly to the gear wheels 99 and 104 as indicated.Additionally, the cable 144 is connected to the engine throttle 146through a leaf spring lever 148. As a result, the position of thethrottle 146 and the indication by the tachometer 142 are integrated asa single mechanicalsignal in the cable 144 to accordingly displace thegear wheels 99 and 104 which are coupled to the racks 96 and 97(offering very little resistance to motion). In operation, if the enginespeed increases and the throttle is opened, it may be desirable toreduce the size of chamber 64 to accomplish an increase in thecompression ratio. To accomplish this change, the gears 99 and 104 arerotated by the cable 144 to drive the gear racks 96 inwardly toward thechamber 64. In this regard, it is to be noted that the cylinderstructures 91 and 33 are free to slide with rotation of the gear chains.

When the cylinder structures 91 and 33 move inwardly they move theirgrooved control sections with relation to the sleeves 82 and 84respectively. When this sliding displacement occurs, lands 150(associated individually with the separate symmetrical structures) aredisplaced inwardly opening ports 152 outwardly. As a result, the flow ofpressurized fluid becomes exclusively through ports 154 (isolating theports 156 from fluid flow). Therefore, pressurizing fluid is notreceived in spaces 158 while it is received in spaces 160. As a result,the spool valve members 88 and 90 receive an outward pressuredifferential causing them to move inwardly along with the affixedsleeves 82 and 84 and the pistons 66 and 68. In this manner the pistons66 and 68 may be moved inwardly to a position indicated in phantom,limited only by abutment with the shoulders 140, and thus varying thecompression ratio of engine as desired.

It is to be noted, that during the operation as described above, thespaces 158 are relieved through ports 160 which communicate with grooves162 that are ported into the annular space between the cylinders 91 and93. As a result, fluid discharged from the space 158 is released fromthe engine and may be captured for controlled exhaust or simplypermitted to escape to the atmosphere.

In the event that the combined mechanical signal resulting from theposition of the throttle 146 and the indication from the tachometer 142,commands a decrease in the compression ratio the sequence of events isexactly opposite to that described above. In such a situation, the space158 is at a pressure substantially elevated over the pressure in thespace 160 with the result that pistons 66 and 68 are displaced outwardlyto increase the volume of the combustion chamber 64. In this regard, thelimit of outward movement by the pistons 66 and 68 occurs when thespaces 160 are closed.

From the above, it is apparent that the system hereof may be effectivelyembodied to adapt compression ratios to instant operating altitude,speed, throttle position, and so on, depending upon the particulardesign and application of the engine. As a result, considerably improvedcombustion can be obtained with greater efficiency and cleaner exhaust,i.e. few live hydrocarbons. As explained, the system involves thecriterion of providing a control signal indicative of the desiredcombustion ratio, then displacing the end members, e.g. opposing pistonsin a cylinder to accommodate the desired combustion ratio by volumetricchange. Of course, as indicated above, the system hereof may be readilyadapted in a wide variety of different forms and may be incorporated ina wide variety of different machines; therefore, the system as disclosedherein is to be deemed merely an exemplary embodiment.

I claim:

1. An internal combustion engine comprising a housing means defining atleast one rotary chamber;

at least one rotor means affixed for rotation in said rotary chamber;

combustion chamber means, defining a substantial cylindrical combustionchamber, for providing combustion gases to drive said rotor means;

means for providing a signal indicative of a desired compression ratiofor said engine; and

means for varying the operating volume of said combustion chamber inaccordance with said signal including at least two piston means slidablydisposed in said combustion chamber and means for controlling saidpiston means in accordance with said signal and including a slidervalve.

2. An internal combustion engine according to Claim 1 including two ofsaid rotor means disposed in perpendicular relationship and furtherincluding means defining a combustion chamber for each of said rotormeans.

3. An internal combustion engine according to Claim 1 wherein said meansfor controlling said piston means includes a spool valve coupled to saidpiston means to slidably displace said piston means in accordance withsaid signal.

4. An internal combustion engine according to Claim 1 wherein saidsignal is indicative of at least the speed of said engine.

5. An internal combustion engine according to Claim 1 wherein said spoolvalve is concentric to said cylindrical combustion chamber.

6. An internal combustion engine according to Claim 1 further includingmeans for supplying fluid pressure from said combustion chamber to drivesaid spool valve.

7. An internal combustion engine according to Claim 1 including two ofsaid piston means and wherein said combustion chamber means furtherincludes a pair of spark plugs fixed in said piston means.

